According to the actual operation data, the operation cost of a typical medium range single aisle commercial transport aircraft will increase 30 dollars if it stays on ground for one more minute, leading to 1 million dollars increase in its life cycle cost. For the purpose of decreasing cost, airlines require the airplanes can turnaround within a short time period. Boarding and deplaning time accounts for more than half of the total turnaround time, however the current estimation method uses empirical data and cannot evaluate the effects from the aircraft design parameters. An aircraft turnaround time estimation model is developed based on the discrete time simulation, which deems boarding and deplaning as a dynamic process. The interaction between one passenger and other passengers, and the interaction between passengers and cabin are taken into account. The model has been compared with the boarding and deplaning data suggested by aircraft manufacturers. A twin aisle airplane is studied and the sensitivity of cabin design parameters is investigated. The results show that the model is suitable for aircraft designers to determine aircraft design parameters to meet the constraint regarding to aircraft turnaround time.